Certain recipes cannot be used with devtool extract / modify / upgrade -
usually because they don't provide any source. Return a specific exit
code (4) so that scripts such as scripts/contrib/devtool-stress.py know
the difference between this and a genuine failure.
(From OE-Core rev: ffd295fed4ab81fc0bd00bb145ef4d72c49584bf)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>